Landsat in New York: Heat Islands, Algal Blooms in the Finger Lakes, and Dying Hemlocks

From New York City's skyline to the forests of the Adirondack Mountains and the countryside of the Allegheny Plateau, New York is full of variety. Bordered by the Atlantic to the east and two of the Great Lakes to the north and west, it has more than 7,600 lakes, ponds and reservoirs and more than 70,000 miles of rivers and streams — and caring for that fresh water is basic to the health of everyone who lives, works or visits there.

Harmful algal blooms (HABs) are a growing threat to the state's waters and people, and images and data from the Landsat satellites give scientists, public health officials and resource managers critical information about them. Here are a few ways Landsat serves New York.

Hot neighborhoods

The New York City Council used Landsat 8 to map relative summer temperatures across the city. Urban heat islands — where days and nights run hotter and air pollution helps trap the heat — can contribute to illness and even death. The Council aims to help residents of the hottest neighborhoods, largely in Brooklyn and Queens, with cooling programs in homes and centers, which could mean fewer deaths and illnesses in future heat waves.

Plans against algal blooms

The New York State Department of Environmental Conservation's Water Quality Rapid Response Team used Landsat 8 to help map HABs on 12 priority lakes. Imagery from 2015 to 2017 helped estimate chlorophyll-a, a pigment that indicates algae. With experts and local stakeholders, the team then wrote HAB action plans for the lakes, tackling causes such as phosphorus pollution — and what was learned on these 12 can help protect other threatened lakes across the state.

The Finger Lakes region in a Landsat scene from June 2018. Five of the Finger Lakes are among the 12 priority lakes with harmful algal bloom action plans. U.S. Geological Survey

Hemlocks under attack

Hemlock woolly adelgid, an invasive insect, has been spreading through eastern hemlock stands in East Coast states, killing the trees. Scientists used Landsat 8 to map hemlock stands in Upstate New York. Adirondack Park and Tug Hill State Forest were long thought too cold for the adelgid to survive, but both are now considered at risk. The maps help partners, including the Department of Environmental Conservation, build risk models and prevention programs for other vulnerable areas, and satellite watching can help track stands already infested — including one recently found at an Adirondack campground.

Landsat for the nation

The USGS National Land Imaging Program supplies satellite imagery and other remote sensing and geospatial data to government, business, universities and the public, with worldwide access to Landsat through the USGS Earth Resources Observation and Science (EROS) Center, which the program funds.

• Landsat is the most widely used land remote sensing source among federal civilian agencies. Local, state, Tribal and federal agencies use it to monitor and forecast what happens on the land — informing everyday decisions on land, water and resources that protect life and property, safeguard the environment, advance science and education, and grow the economy.
• Businesses build customer-specific applications on it for logistics, resource allocation and investment; commercial imaging firms use it to refine products and start new services.
• A 2024 study put Landsat's total annual economic benefit at $25.6 billion, far above what it costs to build and run.
• Landsat 8 and Landsat 9 together cover Earth's land every 8 days. NASA and the USGS are working toward launching Landsat 10 in 2031, with significant improvements, to extend the more-than-50-year Landsat record — the world's longest time series of Earth's land surface.
• Consistent, accurate data offered at no cost let users study wide areas and long-term trends, and cloud computing now puts Landsat into decision tools across government and industry — used every day, like global positioning systems and weather data.

Sources

Based on New York and Landsat, U.S. Geological Survey Fact Sheet 2021–3020, USGS Publications Warehouse, citing the New York City Council (2020), the New York State Department of Environmental Conservation (2021), NASA (2017), Arnold (2020) and Loomis and others (2024); a work of the United States government in the public domain. The fact sheet's New York City heat map (New York City Council, used with permission) and its hemlock woolly adelgid photograph (Bugwood.org, used with permission) are not reproduced.